1. Field of the Invention
This invention generally relates to an electronic document producing device, an electronic document producing method, and a storage medium, which produce a searchable electronic document from an image having distortion.
2. Description of the Related Art
Various conventional methods have been proposed in regard to the correction of a scanned image. Japanese Patent Laid-Open No. S60-65668 (1985) discloses a method of correcting curvature distortion in a bind-in portion of a book. Japanese Patent Laid-Open No. 2002-77578 discloses a method of performing correction of an image for correcting distortion of a photographed image generated due to unevenness in height of a photographing object face by using a distance between upper and lower ends of a manuscript, a distance between an imaging device and the manuscript, and a relative position of the imaging device.
Japanese Patent Laid-Open No. H7-93374 (1995) discloses technology in which character recognition processing is executed on a document image, and the test data as the character recognition result is in advance associated with coordinate information showing a corresponding position of the text data on the document image. Further, upon searching the text, a document image page containing a portion corresponding to the searched text is displayed. In addition, Japanese Patent Laid-Open No. H8-63583 (1996) discloses technology in which text data as a result of executing character recognition processing on a document image is in advance associated with the document image a resolution of which is reduced, and registering the associated result, thus making it possible to produce a searchable document.
In the image correction method according to Japanese Patent Laid-Open No. S60-65668 (1985) and Japanese Patent Laid-Open No. 2002-77578, however, distortion is further generated in the image after the correction due to the correction error that is generated by an estimation error in distortion correction conversion, which may possibly further generate image quality degradation. That is, when the distortion correction processing is executed, further distortion may possibly be generated by the estimation error or the like. Therefore, for a user, there is the possibility that the image after the distortion correction may be more difficult to recognize than the image before the correction.
On the other hand, when character recognition processing is executed on a document image containing distortion, the accuracy of extracting characters from the document image may be deteriorated. As a result, it can occur that character recognition accuracy of an entire document image may be deteriorated.